The domestic cat serves as a valuable animal model in biomedical fields including genetic, neural, ophthalmic, and metabolic research. However, controlled laboratory breeding of feline models is often unsuccessful, which is, in part, due to a lack of information on the basic behavioral-reproductive patterns of cats maintained under laboratory conditions. The overall goal of this project is a series of comprehensive investigations concerning definition of ovarian, behavioral, and endocrine relationships in the domestic cat during prepuberty, estrus, pseudopregnancy, pregnancy, parturition and postpartum interval. Techniques and concepts developed in the latter studies have been applied to selective breeding of various cats used in taxonomic, genetic, and evolutionary analysis of felidae animal models. In addition, recent investigations have revealed the domestic cat to demonstrate unique endocrine responses to administration of the exogenous gonadotropin, human chorionic gonadotropin, an agent used therapeutically in women and laboratory and domestic animals. Overall information obtained in this project is being applied successfully to improve reproductive efficiency and breeding management within feline breeding colonies at NIH.